Project description:Lima bean is an important vegetable processing crop to the Mid-Atlantic U.S. and is highly susceptible to the oomycete pathogen Phytophthora phaseoli, which causes downy mildew. P. phaseoli resides in the same clade with the late blight pathogen, Phytophthora infestans. Genetic resistance and fungicides are used to manage P. phaseoli and often fail. Currently there are no molecular data on this pathosystem. To rectify this situation and determine virulence mechanisms in P. phaseoli we performed a whole-transcriptome analysis using Illumina mRNA-Seq. Six libraries were generated and compared, plate-grown and plant-grown. Our data were normalized and were matched to the P. infestans gene models to obtain the abundance of the sequence reads. This resulted in 10,427 P. phaseoli genes with homology to P. infestans and with expression in either one of the libraries. Upon closer examination, 318 P. phaseoli-homologs matched either known or putative virulence genes in P. infestans. We present data from the whole transcriptome as well as specifically chosen genes from this set of 318. Interestingly, in six libraries from P. phaseoli we found a commonly expressed gene set of 66 out of 563 predicted RXLR genes in P. infestans. The majority of the differentially expressed RxLR and elicitin-like were up-regulated in planta, while the reverse was true for crinkler homologs. These results are discussed with respect to possible pathogenicity mechanisms in P. phaseoli and how they compare to P. infestans. Examination of 3 different conditions of Phytophthora phaseoli
Project description:Lima bean is an important vegetable processing crop to the Mid-Atlantic U.S. and is highly susceptible to the oomycete pathogen Phytophthora phaseoli, which causes downy mildew. P. phaseoli resides in the same clade with the late blight pathogen, Phytophthora infestans. Genetic resistance and fungicides are used to manage P. phaseoli and often fail. Currently there are no molecular data on this pathosystem. To rectify this situation and determine virulence mechanisms in P. phaseoli we performed a whole-transcriptome analysis using Illumina mRNA-Seq. Six libraries were generated and compared, plate-grown and plant-grown. Our data were normalized and were matched to the P. infestans gene models to obtain the abundance of the sequence reads. This resulted in 10,427 P. phaseoli genes with homology to P. infestans and with expression in either one of the libraries. Upon closer examination, 318 P. phaseoli-homologs matched either known or putative virulence genes in P. infestans. We present data from the whole transcriptome as well as specifically chosen genes from this set of 318. Interestingly, in six libraries from P. phaseoli we found a commonly expressed gene set of 66 out of 563 predicted RXLR genes in P. infestans. The majority of the differentially expressed RxLR and elicitin-like were up-regulated in planta, while the reverse was true for crinkler homologs. These results are discussed with respect to possible pathogenicity mechanisms in P. phaseoli and how they compare to P. infestans.
Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease. The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana, and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/P. parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy. The present project aims at analyzing the compatible interaction between A. thaliana roots and P. parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom-designed P. parasitica biochip will enable analyzing of P. parasitica gene expression during the same stages.
Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease.The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/Phytophthora parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy.The present project aims at analyzing the compatible interaction between A. thaliana roots and Phytophthora parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom designed Phytophthora parasitica biochip will enable analyzing of Phytophthora parasitica gene expression during the same stages. The pathosystem involving A. thaliana and Phytophthora parasitica was described in Attard A, Gourgues M, Callemeyn-Torre N, Keller H. 2010. The New phytologist 187: 449–460. The protocol for recovery of RNA from purified appressoria was described in Kebdani N, Pieuchot L, Deleury E, Panabieres F, Le Berre JY, Gourgues M. 2010. New Phytol 185: 248–257.
Project description:Deep sequencing of small RNAs from three Phytophthora species, P. infestans, P. ramorum and P. sojae, was done to systematically analyze small RNA-generating components of Phytophthora genomes. We found that each species produces two distinct small RNA populations that are predominantly 21- or 25-nucleotides long. We present evidence that 25-nucleotide small RNAs are short-interfering RNAs that silence repetitive genetic elements. In contrast, 21-nucleotide small RNAs are associated with inverted repeats, including a novel microRNA family, and may function at the post-transcriptional level. Phytophthora infestans mycelium small RNAs were sequenced and aligned to the P. infestans genome for analysis.